The invention relates to an internal combustion engine having a crankshaft and as at least one cylinder head, which can be traversed by flow at least approximately in the crankshaft axial direction from an inlet duct to an outlet duct and which has valves for opening and closing the ducts.
An internal combustion engine of this type is known, for example, from DE 38 41 710 A1, where, as a consequence of actuating the valves, there is a single camshaft with an inlet cam and an outlet cam. Starting from the cams, the valves are actuated by way of rocker arm shafts, which lie parallel to the valve planes, in that one cam actuates simultaneously two (inlet and/or outlet) valves by way of a rocker arm shaft. In so doing, the cams engage with one end of the rocker arm shaft, and the arms for actuating the valves are arranged along the rocker arm shaft so as to be spaced apart from the cam engagement arm in the rocker arm shaft axial direction. Although this design makes possible a relatively small installation space for a valve controller for controlling a plurality of identical valves, which valves are disposed in the cylinder head, only a limited rotational speed can be reached especially in the case of high valve acceleration.
The invention is based on the task of providing an internal combustion engine of the above-described type. In this context, a valve controller for controlling a plurality of valves that are disposed in a cylinder head requires only a small amount of installation space. At the same time, the internal combustion engine offers an especially direct and rigid transmission path, so that especially in the case of high valve acceleration, high rotational speeds can be reached. In addition, a motor vehicle shall be provided with an internal combustion engine of this type.
This object of the invention is achieved with an internal combustion engine including a crankshaft and at least one cylinder head, which cylinder head can be traversed by flow at least approximately in the crankshaft axial direction from an inlet duct to an outlet duct and which has valves for opening and closing the ducts. A first camshaft and a second camshaft are provided for actuating the valves. Both the first camshaft and the second camshaft are assigned an inlet valve and an outlet valve and are arranged at least approximately parallel to the crankshaft.
In addition, the object of the invention is achieved with a motor vehicle, including an internal combustion engine of this type.
Advantageously, this configuration makes possible an especially compact and space saving design. Only a few components are required so that the cost of production, assembly and maintenance are reduced, and a direct and rigid transmission path is achieved when the valve is actuated.
Especially preferred embodiments and further developments are described herein.
Preferably, the valves are actuated directly by use of cam followers. A direct actuation of the valves by use of bucket tappets is also preferred.
It is very advantageous for the inlet and outlet valve(s) to slope outwards with their cam sided ends in relation to a central plane, sharing the cylinder in the direction of flow. Then, the cylinder head can be configured as a radial head, so that, in particular, design space advantages are achieved. For example, in this way it is possible to gain design space for housing an ignition coil.
According to a preferred further development of the invention, the first camshaft and the second camshaft, as well as the bucket tappets, are disposed in a structurally separate carrier, so that the valve gear is structurally separated from the valves. Thus, it is possible to simplify not only the manufacture (due to being separate) of the cylinder head and the controller carrier with a valve gear, but it is also possible to simplify the assembly, because the valve gear can be pre-assembled separately. It is practical to dispose the first and the second camshaft as well as the cam follower with the cam follower shaft(s) in a structurally separate carrier.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.